This invention relates to dental implants and, more particularly, to submergible implants.
A dental implant, such as that described in Pat. Nos. 3,465,441 and 3,660,899 of the present inventor are used to support an artificial bridge, tooth or other dental prosthesis. The implant has an implant portion, e.g. in the form of a blade, that is secured in the underlying bone in an edentulous span. A linking or neck portion, e.g. in the form of a screw, extends up from the implant portion and is attached to a support or post portion on which the artificial bridge or crown is attached. This type implant is inserted by making an incision in the fibromucosal tissue down to the underlying alveolar ridge crest bone. The tissue is then reflected to expose the bone and a burr is used to create a groove in the bone which is as deep as the implant portion. Using a mallet, the implant portion is tapped into the bone. After the insertion, the tissue is sutured about the neck portion so that the post protrudes above the tissue line. Typically, a few weeks or months are allowed to pass before the dental prosthesis is attached to the post. During this period, bone starts to grow around the implant portion and through holes provided in it, thereby acting to anchor the implant in place before it is stressed by use.
When a removable post is used, such as the screw shown in Pat. No. 3,660,899, the implant blade is made relatively broad, at least at the location of the post, in order to accommodate a threaded aperature into which the post is screwed. This threaded connection creates a a substantial buccal-lingual width or bulge in the blade-type implants. Thus, when an implant is used in the narrow bone areas along the alveolar ridge crest of some patents, the remaining bone may be too narrow. This often leads to bone breakdown or "saucerization" of the resorbing bone in those areas.
Submergible blade implants, such as that shown in U.S. Pat. No. 4,177,562 of A. L. Miller and A. J. Viscido, allow a blade to be inserted in the jawbone for a long period of time before being placed in actual use. With this type of implant the blade is completely submerged in the bone. It is then covered over and allowed to remain in place for several months. Once there has been substantial regrowth of the bone around and through the submerged blade, the tissue is again opened and the post is attached to the blade by the typical screw connection. Because of this screw connection, this submergible blade also has a rather wide buccal-lingual dimension. Further, this design employs additional screws that act to spread the blade. Consequently, this implant may not be suitable for use in narrow bone areas.
Bone areas where either a group of teeth or an implant had to be removed because of loosening, often leave a great deal of bone destruction in the original site. To install an implant in the enlarged area left behind, it is necessary to use a basket or tubular type implant portion such as those disclosed in U.S. patent application Ser. No. 516,184 of the present inventor, which application was filed July 21, 1983 and is entitled "Oral Implant For Oversized Dental Support Openings". Since the bone in the area has already been significantly damaged, it may be desirable to allow a considerable waiting period before the dental prosthesis is applied to the post portion of this implant and it is put into use. However, significant loosening of this implant may occur simply due to contact between the patient's tongue and the neck or post of the implant. Further, the implants in this patent application which are provided with screw type posts, have a generally rounded cross section and may shift in position due to contact with the tongue.
Removable posts are necessary with submergible implants which are to remain out of use for a period of time while the bone regrows. These screw posts are also useful with non-submergible implants because they allow the blade to remain in place when a defective bridge is removed. However, the bridge is usually destroyed when it is removed. In some cases, it is the blade which is defective; but, currently the perfectly good bridge, which is permanently cemented over the posts, must still be destroyed in order to replace the defective implant.